PeerJ Preprints: Aquatic and Marine Chemistryhttps://peerj.com/preprints/index.atom?journal=peerj&subject=1418Aquatic and Marine Chemistry articles published in PeerJ PreprintsOrganic facies variability and paleoenvironmental interpretation of the Early Toarcian of the Pyrenean Basin: the Bizanet and the Pont de Suert sectionshttps://peerj.com/preprints/279772019-09-242019-09-24Carolina FonsecaJoão Graciano Mendonça FilhoCarine LézinLuís Vítor DuartePhilippe Fauré
The Early Toarcian is characterized by major worldwide environmental changes recorded in an organic-rich black shale sedimentation and carbon cycle disturbances, the so-called Toarcian Oceanic Anoxic Event (T-OAE) (e.g. Jenkyns, 2010). This organic-rich sedimentation is particularly recorded in shallow marine epicontinental basins that developed as part of the Toarcian European epicontinental shelf, paleogeographical framework in which the Pyrenean Basin is incorporated (e.g. Fonseca et al., 2018; McArthur et al., 2008). With these premises, the main objective of this study is to assess the organic facies variability and to define the depositional paleoenvironments of two sections from the Pyrenean Basin (Bizanet and Pont de Suert) during the T-OAE, using palynofacies and geochemical (Total Organic Carbon - TOC and insoluble residue - IR) data. The Pyrenean tectonics that occurred between the latest Cretaceous and the Oligocene, deformed, detached and fragmented the substrate resulting in diverse tectonic units (Faure, 2002). The late Pliensbachian-early Toarcian of the Pont de Suert section, located in the South Pyrenean zone, is characterized by the limestone dominated Barre a Pecten Formation (Fm.), and the carbonate and/or argillaceous-carbonate alternation of its three members (alternations of marl and argillaceous limestone of the Calcaires argileux à Spirifèrines Member (Mb.), the argillaceous limestones and marls of the Calcaires argileux et marnes à Soaresirhynchia Mb., and the marl and argillaceous limestone dominated Calcaires argileux à Telothyris Mb.; Faure, 2002). The Bizanet section is located in the eastern Corbières, and is characterized by a 3m thick succession of late Pliensbachian-early Toarcian sediments comprising, at the base, the limestone dominated Barre a Pecten Fm., followed by a sedimentary gap dated to the Tenuicostatum Chronozone, topped by the marly dominated succession of the Bizanet Fm. (black ferruginous marls intercalated with limestones and topped by dolomitic limestones of the Schistes carton Mb., and the black marls of the Argilites noires litées Mb.; Faure, 2002). The geochemical results evidenced that the Bizanet section presents higher TOC contents than the Pont de Suert section, with values reaching 2.03 wt.%. In the Bizanet section IR ranges between 12 wt.% and 82 wt.% and in the Pont de Suert section varies from 13wt.% to 67 wt.%, displaying a similar average value for the two sections (45 wt.%). The palynofacies assemblage is dominated in both sections by the same components, belonging to the Phylum Cnidaria, Class Hydrozoa and Order Hydroida, and are represented by fragments of colonial and non-colonial sessile polypoid forms and free-swimming medusoid forms, with different degrees of amorphization.
(This abstract has been truncated, please see the complete PDF version)
The Early Toarcian is characterized by major worldwide environmental changes recorded in an organic-rich black shale sedimentation and carbon cycle disturbances, the so-called Toarcian Oceanic Anoxic Event (T-OAE) (e.g. Jenkyns, 2010). This organic-rich sedimentation is particularly recorded in shallow marine epicontinental basins that developed as part of the Toarcian European epicontinental shelf, paleogeographical framework in which the Pyrenean Basin is incorporated (e.g. Fonseca et al., 2018; McArthur et al., 2008). With these premises, the main objective of this study is to assess the organic facies variability and to define the depositional paleoenvironments of two sections from the Pyrenean Basin (Bizanet and Pont de Suert) during the T-OAE, using palynofacies and geochemical (Total Organic Carbon - TOC and insoluble residue - IR) data. The Pyrenean tectonics that occurred between the latest Cretaceous and the Oligocene, deformed, detached and fragmented the substrate resulting in diverse tectonic units (Faure, 2002). The late Pliensbachian-early Toarcian of the Pont de Suert section, located in the South Pyrenean zone, is characterized by the limestone dominated Barre a Pecten Formation (Fm.), and the carbonate and/or argillaceous-carbonate alternation of its three members (alternations of marl and argillaceous limestone of the Calcaires argileux à Spirifèrines Member (Mb.), the argillaceous limestones and marls of the Calcaires argileux et marnes à Soaresirhynchia Mb., and the marl and argillaceous limestone dominated Calcaires argileux à Telothyris Mb.; Faure, 2002). The Bizanet section is located in the eastern Corbières, and is characterized by a 3m thick succession of late Pliensbachian-early Toarcian sediments comprising, at the base, the limestone dominated Barre a Pecten Fm., followed by a sedimentary gap dated to the Tenuicostatum Chronozone, topped by the marly dominated succession of the Bizanet Fm. (black ferruginous marls intercalated with limestones and topped by dolomitic limestones of the Schistes carton Mb., and the black marls of the Argilites noires litées Mb.; Faure, 2002). The geochemical results evidenced that the Bizanet section presents higher TOC contents than the Pont de Suert section, with values reaching 2.03 wt.%. In the Bizanet section IR ranges between 12 wt.% and 82 wt.% and in the Pont de Suert section varies from 13wt.% to 67 wt.%, displaying a similar average value for the two sections (45 wt.%). The palynofacies assemblage is dominated in both sections by the same components, belonging to the Phylum Cnidaria, Class Hydrozoa and Order Hydroida, and are represented by fragments of colonial and non-colonial sessile polypoid forms and free-swimming medusoid forms, with different degrees of amorphization.(This abstract has been truncated, please see the complete PDF version)The organic record of Oceanic Anoxic Events: Toarcian vs Cenomanian-Turonianhttps://peerj.com/preprints/279782019-09-242019-09-24Carolina FonsecaJoão Graciano Mendonça FilhoCarine LézinLuís Vítor Duarte
The Mesozoic is marked by periods of profound climatic and paleoceanographic changes of the planet, representing major environmental perturbations and global carbon cycle disturbances, the so-called oceanic anoxic events (OAEs). These events are usually characterized by the deposition of sediments rich in organic matter (OM) which further validates the importance of the characterization of these organic records (e.g. Jenkyns, 2010). Furthermore, the high variability in the expression of these global events could be related to regional factors, which can be assessed through the study of the organic fraction of these records. With these premises is made a discussion about the organic variability, especially focused on petrographic observations, of two major OAE’s that differ in origin, extension and geochemical signature, the Toarcian (T-OAE) and the Cenomanian-Turonian (OAE2) events. For the T-OAE is analyzed a N-S transect of the Toarcian epicontinental seaway to enable the establishment of relationships of confinement, salinity and OM concentration. For the OAE2 the focus is on sections recording the Atlantic and Tethyan affinities to discuss the origin of the anoxia. The T-OAE organic record is characterized by the already established trend in TOC (van de Schootbrugge et al., 2005), with higher values being present in the more northern basins of the European epicontinental seaway (e.g. Dotternhausen) and diminishing towards the south, with lower values registered in the more external basins (e.g. Lusitanian Basin). This is coupled by a decrease in the degree of amorphization of the OM, and a variation in the origin of the amorphous OM, that culminates in its disappearance in the more external Lusitanian Basin (Fonseca et al., 2018; Rodrigues et al., 2016). The OAE2 organic record is marked by high variability, especially connected to differences in oceanic circulation dynamics that differ in the Tethyan and Atlantic domains (e.g. Trabucho-Alexandre et al., 2010). The TOC content of this event reaches higher values than the ones associated with the T-OAE (>30 wt.%), with the organic associations being dominated in the majority of the sections by amorphous OM. Nevertheless, the origin of this component differs and is very much controlled by local conditions. Differences in productivity, connected to the occurrence of intense upwelling in the Atlantic domain, are also observed. The organic facies variability and the differences in paleoenvironmental depositional contexts observed in the studied sections are associated with the regional character of both the T-OAE and the OAE2. These are mainly attributed to differences in paleogeography, paleogeomorphology and oceanic circulation patterns. Furthermore, there are clear differences in the organic content of both events, showing that is not only their origin, extension and geochemical characteristics that differ but also their organic signature.
The Mesozoic is marked by periods of profound climatic and paleoceanographic changes of the planet, representing major environmental perturbations and global carbon cycle disturbances, the so-called oceanic anoxic events (OAEs). These events are usually characterized by the deposition of sediments rich in organic matter (OM) which further validates the importance of the characterization of these organic records (e.g. Jenkyns, 2010). Furthermore, the high variability in the expression of these global events could be related to regional factors, which can be assessed through the study of the organic fraction of these records. With these premises is made a discussion about the organic variability, especially focused on petrographic observations, of two major OAE’s that differ in origin, extension and geochemical signature, the Toarcian (T-OAE) and the Cenomanian-Turonian (OAE2) events. For the T-OAE is analyzed a N-S transect of the Toarcian epicontinental seaway to enable the establishment of relationships of confinement, salinity and OM concentration. For the OAE2 the focus is on sections recording the Atlantic and Tethyan affinities to discuss the origin of the anoxia. The T-OAE organic record is characterized by the already established trend in TOC (van de Schootbrugge et al., 2005), with higher values being present in the more northern basins of the European epicontinental seaway (e.g. Dotternhausen) and diminishing towards the south, with lower values registered in the more external basins (e.g. Lusitanian Basin). This is coupled by a decrease in the degree of amorphization of the OM, and a variation in the origin of the amorphous OM, that culminates in its disappearance in the more external Lusitanian Basin (Fonseca et al., 2018; Rodrigues et al., 2016). The OAE2 organic record is marked by high variability, especially connected to differences in oceanic circulation dynamics that differ in the Tethyan and Atlantic domains (e.g. Trabucho-Alexandre et al., 2010). The TOC content of this event reaches higher values than the ones associated with the T-OAE (>30 wt.%), with the organic associations being dominated in the majority of the sections by amorphous OM. Nevertheless, the origin of this component differs and is very much controlled by local conditions. Differences in productivity, connected to the occurrence of intense upwelling in the Atlantic domain, are also observed. The organic facies variability and the differences in paleoenvironmental depositional contexts observed in the studied sections are associated with the regional character of both the T-OAE and the OAE2. These are mainly attributed to differences in paleogeography, paleogeomorphology and oceanic circulation patterns. Furthermore, there are clear differences in the organic content of both events, showing that is not only their origin, extension and geochemical characteristics that differ but also their organic signature.Variation of kerogen assemblages and δ13CKerogen in Lower Toarcian successions of the southern Tethyan marginhttps://peerj.com/preprints/279452019-09-112019-09-11Bruno RodriguesRicardo SilvaJoão Graciano Mendonça FilhoLuís Vítor DuarteMatías ReolidDriss Sadki
The early Toarcian Oceanic Anoxic Event (T-OAE) is associated with an “excess” of C12 in the atmospheric and ocean carbon reservoirs and widespread occurrence of organic-rich facies around the globe. The T-OAE is recorded as a pronounced negative carbon isotopic excursion (CIE) in carbonates, fossil wood, and kerogens at the base of the Serpentinum (=Falciferum=Levisoni) Chronozone, positioned within a broad δ13C positive trend initiated at the base of the Lower Toarcian. Contrasts in deposition and preservation of OM between the northern and southern Tethyan margins are observed during the T-OAE. Several sections of the northern Tethyan margin are enriched in OM, whereas in the southern Tethyan margin, organic-rich facies are spatially and temporally restricted and have lower TOC. This dichotomy reflects differentiated depositional and environmental conditions between the two margins, controlled by the interplay of local, regional, and global constraints (distinct palaeogeographical location, OM type and source, palaeoceanography, climate, tectonics, etc.). This study investigates the variation of kerogen assemblages and δ13CKerogen in the Upper Pliensbachian–Lower Toarcian interval along the southern Tethyan margin, i.e. Lusitanian Basin (Portugal), Betic Cordillera (Spain), and Middle Atlas (Morocco). The objective is to contribute to the understanding of the paleoenvironmental variables and dynamics that influenced deposition and preservation of OM during the Late Pliensbachian–Early Toarcian in the Tethyan region. Preliminary analysis revealed that Upper Pliensbachian–Lower Toarcian kerogen assemblages from the Betic Cordillera, Lusitanian, and Middle Atlas basins are dominated by terrestrial particles (phytoclasts and sporomorphs) and have relatively more positive δ13C values when compared with correlative North-European sections. In the Lusitanian Basin and Betic Cordillera, the T-OAE negative CIE is observed in the δ13CKerogen record and is accompanied by an increase in terrestrial palynomorphs, non-opaque phytoclasts (NOP), and cuticle fragments. These increases are in line with the posited intensification of continental weathering, acceleration of the hydrological cycle, and increased export of terrestrial OM into marine environments during the T-OAE.
The early Toarcian Oceanic Anoxic Event (T-OAE) is associated with an “excess” of C12 in the atmospheric and ocean carbon reservoirs and widespread occurrence of organic-rich facies around the globe. The T-OAE is recorded as a pronounced negative carbon isotopic excursion (CIE) in carbonates, fossil wood, and kerogens at the base of the Serpentinum (=Falciferum=Levisoni) Chronozone, positioned within a broad δ13C positive trend initiated at the base of the Lower Toarcian. Contrasts in deposition and preservation of OM between the northern and southern Tethyan margins are observed during the T-OAE. Several sections of the northern Tethyan margin are enriched in OM, whereas in the southern Tethyan margin, organic-rich facies are spatially and temporally restricted and have lower TOC. This dichotomy reflects differentiated depositional and environmental conditions between the two margins, controlled by the interplay of local, regional, and global constraints (distinct palaeogeographical location, OM type and source, palaeoceanography, climate, tectonics, etc.). This study investigates the variation of kerogen assemblages and δ13CKerogen in the Upper Pliensbachian–Lower Toarcian interval along the southern Tethyan margin, i.e. Lusitanian Basin (Portugal), Betic Cordillera (Spain), and Middle Atlas (Morocco). The objective is to contribute to the understanding of the paleoenvironmental variables and dynamics that influenced deposition and preservation of OM during the Late Pliensbachian–Early Toarcian in the Tethyan region. Preliminary analysis revealed that Upper Pliensbachian–Lower Toarcian kerogen assemblages from the Betic Cordillera, Lusitanian, and Middle Atlas basins are dominated by terrestrial particles (phytoclasts and sporomorphs) and have relatively more positive δ13C values when compared with correlative North-European sections. In the Lusitanian Basin and Betic Cordillera, the T-OAE negative CIE is observed in the δ13CKerogen record and is accompanied by an increase in terrestrial palynomorphs, non-opaque phytoclasts (NOP), and cuticle fragments. These increases are in line with the posited intensification of continental weathering, acceleration of the hydrological cycle, and increased export of terrestrial OM into marine environments during the T-OAE.The occurrence of pharmaceutical waste in different parts of the world: A scoping reviewhttps://peerj.com/preprints/279512019-09-102019-09-10Kim Yun JinMuhammad Shahzad Aslam
Pharmaceutical waste in our ecosystem is the huge burden for our future generations, especially in developing countries. It can be in every place even in drinking water after water treatment. It was observed the presence of over the counter drugs such as ibuprofen, naproxen, acetaminophen and antibiotic such as sulfamethoxazole, trimethoprim, erythromycin the most in the environment. Among all result, Carbamazepine which is known to treat epilepsy was found the most in the environment when the results were compiled from different parts of the world due to its low biodegradable properties. The current article is focused on the occurrence of pharmaceutical waste in the last eight years (January 2010- July 2018) published research work.
Pharmaceutical waste in our ecosystem is the huge burden for our future generations, especially in developing countries. It can be in every place even in drinking water after water treatment. It was observed the presence of over the counter drugs such as ibuprofen, naproxen, acetaminophen and antibiotic such as sulfamethoxazole, trimethoprim, erythromycin the most in the environment. Among all result, Carbamazepine which is known to treat epilepsy was found the most in the environment when the results were compiled from different parts of the world due to its low biodegradable properties. The current article is focused on the occurrence of pharmaceutical waste in the last eight years (January 2010- July 2018) published research work.Example application of a continuous lake trophic state index on lakes with limited datahttps://peerj.com/preprints/279132019-08-212019-08-21Farnaz NojavanBetty J KreakieJeffrey W HollisterSong Qian
Lake trophic state indices have long been used to provide a measure of the trophic state of lakes. Over time it has been determined that these indices perform better when they utilize multiple metrics and provide a continuous measurement of trophic state. We utilize such a method for trophic state that is based upon a Proportional Odds Logistic Regression (POLR) model and extend this model with a Bayesian multilevel model that predicts nutrient concentrations from universally available GIS data. This Bayesian multilevel model provides relatively accurate measures of trophic state and has an overall accuracy of 60%. The approach illustrates a method for estimating a continuous, mutli-metric trophic state index for any lake in the United States. Future improvements to the model will focus on improving overall accuracy and use variables that are more sensitive to change over time.
Lake trophic state indices have long been used to provide a measure of the trophic state of lakes. Over time it has been determined that these indices perform better when they utilize multiple metrics and provide a continuous measurement of trophic state. We utilize such a method for trophic state that is based upon a Proportional Odds Logistic Regression (POLR) model and extend this model with a Bayesian multilevel model that predicts nutrient concentrations from universally available GIS data. This Bayesian multilevel model provides relatively accurate measures of trophic state and has an overall accuracy of 60%. The approach illustrates a method for estimating a continuous, mutli-metric trophic state index for any lake in the United States. Future improvements to the model will focus on improving overall accuracy and use variables that are more sensitive to change over time.Energy use in water purification as criterion for selecting drinking water treatment technologieshttps://peerj.com/preprints/277612019-05-272019-05-27Wenfa Ng
Quality of produced water is usually the criterion for selecting between different desalination technologies for turning seawater into drinking water. However, contemporary trend in drinking water treatment sees a convergence between different technologies for the same water quality. Hence, how do different desalination technologies differentiate amongst each other? Awareness of climate change impact as well as price of produced water, energy use per unit of treated water is an oft-used criterion for assessing the effectiveness and efficiency of different desalination technologies. Specifically, comparing multi-effect flash evaporation and reverse osmosis, the latter enjoys a significant energy use advantage given the lack of the need for converting water into the vapor phase as in multi-effect flash evaporation. Thus, energy used in producing drinking water is significantly higher in multi-effect flash evaporation compared to the high pressure process of reverse osmosis. From the operation perspective, reverse osmosis also benefits from its ability to scale linearly in increasing water production capacity through addition of extra membrane modules, which is not the case for multi-effect flash evaporation where a new distillation column is required for significant increase in production capacity. Collectively, with the same quality of water produced by different desalination technologies, comparison between different technologies increasingly relies on the energy use per unit of produced water. Using this criterion, reverse osmosis membrane desalination has a significant advantage relative to multi-effect flash evaporation in energy cost, which translates to a lower price of produced water.
Quality of produced water is usually the criterion for selecting between different desalination technologies for turning seawater into drinking water. However, contemporary trend in drinking water treatment sees a convergence between different technologies for the same water quality. Hence, how do different desalination technologies differentiate amongst each other? Awareness of climate change impact as well as price of produced water, energy use per unit of treated water is an oft-used criterion for assessing the effectiveness and efficiency of different desalination technologies. Specifically, comparing multi-effect flash evaporation and reverse osmosis, the latter enjoys a significant energy use advantage given the lack of the need for converting water into the vapor phase as in multi-effect flash evaporation. Thus, energy used in producing drinking water is significantly higher in multi-effect flash evaporation compared to the high pressure process of reverse osmosis. From the operation perspective, reverse osmosis also benefits from its ability to scale linearly in increasing water production capacity through addition of extra membrane modules, which is not the case for multi-effect flash evaporation where a new distillation column is required for significant increase in production capacity. Collectively, with the same quality of water produced by different desalination technologies, comparison between different technologies increasingly relies on the energy use per unit of produced water. Using this criterion, reverse osmosis membrane desalination has a significant advantage relative to multi-effect flash evaporation in energy cost, which translates to a lower price of produced water.Bioactivity of compounds secreted by symbiont bacteria of Nudibranchs from Indonesiahttps://peerj.com/preprints/277452019-05-202019-05-20Rhesi KristianaGilles BedouxGerard PalsI Wayan MudiantaLaure TaupinChristel MartyMeezan Ardhanu AsagabaldanDiah AyuningrumAgus TriantoNathalie BourgougnonOcky Karna RadjasaAgus Sabdono
The aim of this work was to isolate bacterial symbionts from nudibranchs and subsequently to determine anti-Methicillin resistant Staphylococcus aureus (MRSA), cytotoxicity and anti-HSV-1 activities of bio-compounds. Fifteen species of nudibranchs were collected from Karimunjawa and five species from Bali, respectively. A total of 245 bacteria isolates were obtained. The anti-MRSA activity screening activity indicated 2 isolates of active bacteria. Ethyl acetate extracts from supernatants, indicating secreted compounds, showed an inhibition zone against MRSA at concentrations of 500-1000µg/ml. DNA sequence analysis showed that the strainKJB-07 from Phyllidia coelestis was closely related to Pseudoalteromonas rubra, the strain NP31-01 from Phyllidia varicosa was closely related to Virgibacillus salarius. The extract of P. rubra was cytotoxic to Vero cells at a concentration of 75 µg/ml. The extract of V. salarius presented no cytotoxicity at concentrations of 5-1000 µg/ml. No anti-HSV-1 was observed. This is the first reported study describing research on anti-MRSA, cytotoxicity and anti-HSV-1 activity of bacterial symbionts from the viscera of nudibranch. Compounds produced and secreted byPseudoalteromonas rubra and Virgibacillus salarius, symbionts of Nudibranch, had potential anti-MRSA activity. Extracts from P. rubra showed cytotoxic effects on Vero cells, whereas extracts from V. salarius did not show cytotoxic effects. Three compounds were identified by LC/MS after purification from culture supernatant.
The aim of this work was to isolate bacterial symbionts from nudibranchs and subsequently to determine anti-Methicillin resistant Staphylococcus aureus (MRSA), cytotoxicity and anti-HSV-1 activities of bio-compounds. Fifteen species of nudibranchs were collected from Karimunjawa and five species from Bali, respectively. A total of 245 bacteria isolates were obtained. The anti-MRSA activity screening activity indicated 2 isolates of active bacteria. Ethyl acetate extracts from supernatants, indicating secreted compounds, showed an inhibition zone against MRSA at concentrations of 500-1000µg/ml. DNA sequence analysis showed that the strainKJB-07 from Phyllidia coelestis was closely related to Pseudoalteromonas rubra, the strain NP31-01 from Phyllidia varicosa was closely related to Virgibacillus salarius. The extract of P. rubra was cytotoxic to Vero cells at a concentration of 75 µg/ml. The extract of V. salarius presented no cytotoxicity at concentrations of 5-1000 µg/ml. No anti-HSV-1 was observed. This is the first reported study describing research on anti-MRSA, cytotoxicity and anti-HSV-1 activity of bacterial symbionts from the viscera of nudibranch. Compounds produced and secreted byPseudoalteromonas rubra and Virgibacillus salarius, symbionts of Nudibranch, had potential anti-MRSA activity. Extracts from P. rubra showed cytotoxic effects on Vero cells, whereas extracts from V. salarius did not show cytotoxic effects. Three compounds were identified by LC/MS after purification from culture supernatant.Difficulty in dislodging biofilms from inner surface of drinking water pipelineshttps://peerj.com/preprints/276282019-04-022019-04-02Wenfa Ng
Microorganisms tend to adhere to any surface in contact with water and forms architecturally complex community of organisms known as biofilms. Biofilms reside on many environmental surfaces and has been utilized in wastewater treatment. However, their presence in drinking water pipelines is undesirable and is the subject of intense research effort aimed at characterizing their cellular composition, mechanical and physiological properties, and susceptibility to various environmental and antimicrobial challenges. Subsisting on the small amount of assimilable organic carbon in drinking water, biofilms in drinking water pipelines are difficult to dislodge via a variety of methods such as pulsating flow and elevation of residual disinfectant concentration. Indeed, potable drinking water poses severe constraints to the use of chemical additives for inhibiting the growth of biofilms. Hence, mechanical methods such as increasing hydraulic pressure for enabling biofilm dislodgement through elevated shear stress are preferred. However, periods of stagnation are unavoidable in drinking water pipelines, and microbes have been known to repopulate to areas of pipelines where biofilms have previously been dislodged. More importantly, possibility exists that microbes in biofilms have adapted to fluctuating shear stress through a combination of secretion of adherent extracellular polymeric substances (EPS) and activation of cellular responses to mechanical stress sensed by the cell envelope. So, how do we dislodge biofilms from the inner surfaces of drinking water pipelines? Or, if dislodgement of biofilm is difficult to achieve, how do we manage the problem? One approach to mitigate the problem would be to maintain sufficient residual disinfectant in drinking water to both ensure the safety of drinking water as well as imposing a constant survival pressure on microbes in drinking water biofilms. Even if live cells are dislodged from biofilms into drinking water, presence of a high residual disinfectant concentration would render the cells inactivated. Beyond approved residual disinfectant such as monochloramine, use of other antimicrobial agents appear limited due to concerns for public health and safety. Hence, there exists a narrow operating window in which only residual disinfectant concentration and frequency and strength of pulsating flow could be used as levers to control biofilm growth on inner surfaces of drinking water pipelines. Overall, the problem of dislodging drinking water biofilms from pipelines is an important one, but there is paucity of new methods for controlling biofilm growth and facilitating their dislodgement due to constrains imposed by drinking water safety. Hence, focus has shifted to development of new pipelines surfaces that prevent the adherence of microbes and biofilm formation. Efforts in this direction may provide answers in resolving the long-standing question of preventing biofilm growth in drinking water pipelines.
Microorganisms tend to adhere to any surface in contact with water and forms architecturally complex community of organisms known as biofilms. Biofilms reside on many environmental surfaces and has been utilized in wastewater treatment. However, their presence in drinking water pipelines is undesirable and is the subject of intense research effort aimed at characterizing their cellular composition, mechanical and physiological properties, and susceptibility to various environmental and antimicrobial challenges. Subsisting on the small amount of assimilable organic carbon in drinking water, biofilms in drinking water pipelines are difficult to dislodge via a variety of methods such as pulsating flow and elevation of residual disinfectant concentration. Indeed, potable drinking water poses severe constraints to the use of chemical additives for inhibiting the growth of biofilms. Hence, mechanical methods such as increasing hydraulic pressure for enabling biofilm dislodgement through elevated shear stress are preferred. However, periods of stagnation are unavoidable in drinking water pipelines, and microbes have been known to repopulate to areas of pipelines where biofilms have previously been dislodged. More importantly, possibility exists that microbes in biofilms have adapted to fluctuating shear stress through a combination of secretion of adherent extracellular polymeric substances (EPS) and activation of cellular responses to mechanical stress sensed by the cell envelope. So, how do we dislodge biofilms from the inner surfaces of drinking water pipelines? Or, if dislodgement of biofilm is difficult to achieve, how do we manage the problem? One approach to mitigate the problem would be to maintain sufficient residual disinfectant in drinking water to both ensure the safety of drinking water as well as imposing a constant survival pressure on microbes in drinking water biofilms. Even if live cells are dislodged from biofilms into drinking water, presence of a high residual disinfectant concentration would render the cells inactivated. Beyond approved residual disinfectant such as monochloramine, use of other antimicrobial agents appear limited due to concerns for public health and safety. Hence, there exists a narrow operating window in which only residual disinfectant concentration and frequency and strength of pulsating flow could be used as levers to control biofilm growth on inner surfaces of drinking water pipelines. Overall, the problem of dislodging drinking water biofilms from pipelines is an important one, but there is paucity of new methods for controlling biofilm growth and facilitating their dislodgement due to constrains imposed by drinking water safety. Hence, focus has shifted to development of new pipelines surfaces that prevent the adherence of microbes and biofilm formation. Efforts in this direction may provide answers in resolving the long-standing question of preventing biofilm growth in drinking water pipelines.Detection of toxic materials at Death Valley and Death Spring, a new ecosystem in Tashan District, Southern Iranhttps://peerj.com/preprints/276042019-03-202019-03-20Jalal ValiallahiReza Fatemi Motlagh
Death Valley and its stream form a unique landscape in the Tashan district of southern Iran. The water from the headstream of Death Spring to 100 meters downstream and the air around it are lethally dangerous and cause death. The color of the stream beds changes to five different colors. In this study, sampling of sediment and water took place in two seasons and at five stations. Historical information about the area was also collected and analyzed. The heavy metal concentrations in the water and sediment were high; in successive order from high to low, they were Fe > Al > Ag > Pb > Zn > Mn > As > Cu > Cr > Ni > Cd > Co > Sb. The toxic gas is H2S, and the treated concentration of this gas rises up to 410 ppm making the surrounding air toxic as well. The Gas emission has Geological origin. At the source of Death spring the Sulfur compounds in the water, soil, and sediment do not allow the growth of any macroscopic plants or animals. The current study aimed to identify the eco-touristic capacities and mortal danger in this valley, and to carry out environmental action plans, such as installing warning plates and notes to protect people and animals, so that all can benefit from the clean air and mineral water of 7 clean springs at the higher regions of Death Spring and enjoy the pleasant landscape of this area without being injured by the lethal gas of Death Valley. Other wonders of this area are also introduced.
Death Valley and its stream form a unique landscape in the Tashan district of southern Iran. The water from the headstream of Death Spring to 100 meters downstream and the air around it are lethally dangerous and cause death. The color of the stream beds changes to five different colors. In this study, sampling of sediment and water took place in two seasons and at five stations. Historical information about the area was also collected and analyzed. The heavy metal concentrations in the water and sediment were high; in successive order from high to low, they were Fe > Al > Ag > Pb > Zn > Mn > As > Cu > Cr > Ni > Cd > Co > Sb. The toxic gas is H2S, and the treated concentration of this gas rises up to 410 ppm making the surrounding air toxic as well. The Gas emission has Geological origin. At the source of Death spring the Sulfur compounds in the water, soil, and sediment do not allow the growth of any macroscopic plants or animals. The current study aimed to identify the eco-touristic capacities and mortal danger in this valley, and to carry out environmental action plans, such as installing warning plates and notes to protect people and animals, so that all can benefit from the clean air and mineral water of 7 clean springs at the higher regions of Death Spring and enjoy the pleasant landscape of this area without being injured by the lethal gas of Death Valley. Other wonders of this area are also introduced.Estimating nitrogen and phosphorus concentrations in streams and rivers across the contiguous United States: a machine learning frameworkhttps://peerj.com/preprints/275852019-03-132019-03-13Longzhu ShenGiuseppe AmatulliTushar SethiPeter RaymondSami Domisch
Nitrogen (N) and Phosphorus (P) are essential nutrients for life processes in water bodies but in excessive quantities, they are a significant source of aquatic pollution. Eutrophication has now become widespread due to such an imbalance, and is largely attributed to anthropogenic activity. In view of this phenomenon, we present a new dataset and statistical method for estimating and mapping elemental and compound con- centrations of N and P at a resolution of 30 arc-seconds (∼1 km) for the conterminous US. The model is based on a Random Forest (RF) machine learning algorithm that was fitted with environmental variables and seasonal N and P concentration observations from 230,000 stations spanning across US stream networks. Accounting for spatial and temporal variability offers improved accuracy in the analysis of N and P cycles. The algorithm has been validated with an internal and external validation procedure that is able to explain 70-83% of the variance in the model. The dataset is ready for use as input in a variety of environmental models and analyses, and the methodological framework can be applied to large-scale studies on N and P pollution, which include water quality, species distribution and water ecology research worldwide.
Nitrogen (N) and Phosphorus (P) are essential nutrients for life processes in water bodies but in excessive quantities, they are a significant source of aquatic pollution. Eutrophication has now become widespread due to such an imbalance, and is largely attributed to anthropogenic activity. In view of this phenomenon, we present a new dataset and statistical method for estimating and mapping elemental and compound con- centrations of N and P at a resolution of 30 arc-seconds (∼1 km) for the conterminous US. The model is based on a Random Forest (RF) machine learning algorithm that was fitted with environmental variables and seasonal N and P concentration observations from 230,000 stations spanning across US stream networks. Accounting for spatial and temporal variability offers improved accuracy in the analysis of N and P cycles. The algorithm has been validated with an internal and external validation procedure that is able to explain 70-83% of the variance in the model. The dataset is ready for use as input in a variety of environmental models and analyses, and the methodological framework can be applied to large-scale studies on N and P pollution, which include water quality, species distribution and water ecology research worldwide.